Apparatus for drying materials

ABSTRACT

Apparatus and method for continuous drying of materials including means and steps for passing the material to be dried into a drying chamber having a plurality of drying zones; uniformly directing heated fluid through the drying zones, each drying zone having means to direct the heated fluid substantially uniformly over the surfaces of the material to be dried; and having discharge fluid collecting means in communication with the drying zones to collect the discharged fluid, and means for moving substantially all of the discharged fluid through a heat exchanger means so as to uniformly heat substantially all of the discharged fluid to a desired temperature and means to conduct the uniformly heated fluid to the distributing means and temperature control means to maintain the fluid temperature in the drying chamber and then passing fluid through the distributing means whereby the uniformly heated fluid is conducted through the drying zones to continuously dry the material uniformly.

[ Sept. 18, 1973 APPARATUS FOR DRYING MATERIALS [75] Inventors: DavidMcCreary, Latham; John McCreary, Newtonville; Harvey Anderson, Elnora,all of NY.

[73] Assignee: McCreary Machine Works, Cohoes,

22 Filed: Apr. 21, 1971 21 Appl. No.: 136,797

[52] 0.8. CI 34/156, 34/46, 34/47, 34/158 [51] Int. Cl. F26b 13/00 [58]Field of Search 34/46, 47, 48, 50, 34/155, 156, 158, 160

[56] References Cited UNITED STATES PATENTS 3,048,383 8/1962 Champin34/156 3,680,218 8/1972 Belue et al. 34/156 1,976,280 10/1934 Fischer34/46 X 2,038,457 4/1936 Ventunni 34/155 2,083,141 6/1937 Buck 34/158 X2,236,430 3/1941 Hurxthal.... 34/162 X 2,920,398 1/1960 Liljenstrom....34/46 3,079,910 3/1963 Bloom et al. 126/91 A 3,259,995 7/1966 Powischill34/50 X 3,403,454 10/1968 Smith 34/155 X Smith 34/1 Smith 34/48 PrimaryExaminer-Carroll B. Dority, Jr. Attorney-Kane, Dalsimer, Kane, Sullivan& Kurucz [57] ABSTRACT Apparatus and method for continuous drying ofmaterials including means and steps for passing the material to be driedinto a drying chamber having a plurality of drying zones; uniformlydirecting heated fluid through the drying zones, each drying zone havingmeans to direct the heated fluid substantially uniformly over thesurfaces of the material to be dried; and having discharge fluidcollecting means in communication with the drying zones to collect thedischarged fluid, and means for moving substantially all of thedischarged fluid through a heat exchanger means so as to uniformly heatsubstantially all of the discharged fluid to a desired temperature andmeans to conduct the uniformly heated fluid to the distributing meansand temperature control means to maintain the fluid temperature in thedrying chamber and then passing fluid through the distributing meanswhereby the uniformly heated fluid is conducted through the drying zonesto continuously dry the material uniformly.

8 Claims, 10 Drawing Figures PATENTEBSEPWIHH 3.758.960

SHEET 1 0F 7 ATTORNEYS PATENTED SEPI 81975 SHEEIZUF? ATTORN EYE PATENTEDSEP1 8 I973 SHEET '4 Bf 7 ATTORNEYS PATENTEBSEPIBIQH 3,758,960

SHEET 6 BF 7 z, ywfawm ATTORNEYS APPARATUS FOR DRYING MATERIALSBACKGROUND OF THE INVENTION Various methods and apparatus have been usedto dry materials, particularly web like materials for the textileindustry. Where material is to be dried or otherwise treated andfinished, it is generally suspended between a pair of moving rails andthen passed through a drying apparatus. Such a device is commonlyreferred to as a tenter machine having a drying chamber coupled thereto.The tenter conveys the fabric through the drying chamber which includesmultiple units or modules separately controlled. Each unit uses a heatexchanger to heat the air which is circulated through that unit. Tocompensate for the drop in temperature of the returned air, thetemperature in succeeding units is increased to dry the material and istherefore nonuniform. Thus, because of the use of multiple heatexchangers, a constant supply of heated air at uniform temperature isimpossible. Other drying units use a combination of air and superheatedsteam to try and maintain a uniform temperature. However, these dryershave the same problems and difl'iculties of the type described above.

Further, the prior art dryers provide means for passing the heated airor heated air and superheated steam through the web material generallyfrom below the moving material which causes a billow to form and,consequently, can alter the physical'characteristics of the materialsuch as drape, hand and resiliency at drying temperatures particularlyif the material is a synthetic material. Also, these dryers will ruin ordestroy the material to be dried if the machine for any reason is causedto stop. The drying zones cannot be brought to ambient temperatures toprevent the destruction, burning or discoloration of the web materialwithin the drying apparatus.

SUMMARY OF THE INVENTION This invention generally relates to dryingapparatus particularly adapted for use in textile industries inconnection with tenter machines. The invention contemplates providing adrying apparatus for drying materials comprising a drying chamber havinga plurality of drying zones therein, each drying zone having a pair ofconduit means for directing heated fluid to each side of the material tobe dried, a fluid discharge chamber coupled to the conduit means fromeach drying zone and disposed remotely from the conduit means forconducting discharged fluid from the drying zone to a heating means touniformly heat the discharged fluid to a desired temperature, heatexchanger means for heating substantially all of the discharged fluidconducted therethrough, distributing means mounted to the drying zonesand coupled thereto to conduct the uniformly heated fluid to each dryingzone and then passing the uniformly heated fluid through-thedistributing means whereby the uniformly heated fluid is conductedthrough conduit means in the drying zone to uniformly dry the materialpassing therethrough.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 3 is a sectional view taken alonglines 33 of FIG. 1.

FIG. 4 is a sectional view taken along lines 4-4 of FIG. 3 showing theheat exchanger section and path of fluid taken through the heatexchanger.

FIG. 5 is a sectional view taken along lines 5-5 of FIG. 3.

FIG. 6 is a sectional view taken along lines 6-6 of FIG. 1.

FIGS. 7-10 are schematic illustrations which show the controls forregulating the flow of fluid through the drying apparatus and means fordistributing the fluid therethrough.

DESCRIPTION OF THE PREFERRED EMBODIMENTS For a better understanding ofthe invention, reference is made to the drawings, particularly FIGS. 1through 6. The drying apparatus embodied in FIGS. 1-6 is generallyindicated by numeral 10 and is enclosed around a tenter frame, shown ina fragmentary section only. The drying apparatus is formed with ahorizontal passage 12 which extends therethrough so as to provide a pathfor the textile material M." Textile material M is preferably removablymounted on a high speed pin type tenter chains 16 by pins 17 such asdisclosed in US Pat. No. 3,050,816. Drying apparatus 10 is mountedaround the tenter chains so that tenter chains 16 and the textilematerial M as shown in FIGS. 3, 5 and 6 pass through the entire lengthof the drying apparatus 10 through passage 12.

Drying apparatus 10 is generally rectangular in shape and is providedwith a top or roof portion 20, a bottom or floor portion 22, side walls24 and 26, and front and rear walls 28 and 30. Front and rear walls 28and 30 are formed with horizontally extending openings forming theentrance and exit openings 13 and 14 of passage 12.

Drying apparatus 10 is constructed having a plurality of means formingdrying zones 32, 33, 34, 35 and 36 of similar structure. Thus, indescribing the portions of drying zone 32, the similar portions ofdrying zones 33, 34, 35 and 36 need not be described. Means formingdrying zone 32 is shown most clearly in FIG. 3 and is enclosed by top,bottom and side walls 20, 22, 24 and 26.

Spaced conduits comprising an upper pair 38 and a lower pair 40 aredisposed in parallel relationship to each other and extend across thedrying apparatus so as to be positioned above and below tenter chains16. Upper conduits 38 and lower conduits 40 are formed so that thesurfaces lying in close proximity to the tenter chains 16 are providedwith openings 42. The conduits 38 and 40 are mounted in position byupstanding partition 44. Partition 44 is formed with openingssubstantially equal to the openings formed by conduits 38 and 40 so thatfluid may pass into the conduits and through the openings 42 so that thefluid passing through openings 42 comes in contact with the upper andlower surfaces of the material M to be dried. Partition 44 is spacedfrom side wall 26 which provides a passage for heated fluid to enterconduits 38 and 40 as shown by the arrows in FIG. 3.

An unhoused type fan 50 is mounted on partition 44 so as to directheated fluid from the heating zone through conduits 38 and 40 so thatthe heated fluid contacts the textile material M by passing throughopenings 42 of conduits 38 and 40. The heated fluid contacts thesurfaces of textile material M substantially uniformly over the entireupper and lower surfaces so that the textile material M is supported bythe fluid and lies substantially in a horizontal plane while passingthrough passage 12 of the drying apparatus. The heated fluid impinges onthe material M from above and below and always at a desired settemperature. This promotes uniform drying from each side of the materialM as well as a gradual even drying throughout the entire length of thedrying apparatus.

As will be explained hereinafter, conduits 38 and 40 may be providedwith means to automatically open damper devices mounted at the endsthereof to provide a bypass for heated air if the tenter chains shouldcease to operate for any reason. Such a system obviates the possibilityof loss of material M due to excessive heat that may be present in thedrying apparatus. Also, provisions are made for bypassing substantiallyall of the fluid through the heating means while the drying apparatus isnot in operation. This obviates any damage to material that may be inpassage 12 of the drying apparatus.

Partition 46 is spaced from side wall 24 and is filled with filters toprovide a return fluid plenum of exhausted fluid from the dischargechamber 52 which is formed by floor 22 bottom 62, portions of front andrear walls 28 and 30, portions of partition 44 and side wall 24. Thechamber 52 provides fluid communication between the heated fluid beingconducted through conduits 38 and 40 and the discharged fluid beingconducted to the heating means. Note in FIG. 3 direction of the arrowswhich indicate the path of the fluid as it passes through drying zone32. Mounted in partition 46 are a plurality of filters or screens 47,which remove any lint that may be present in the discharge fluid afterpassing over the surfaces of textile material M. The screens arepreferably removably mounted in partition 46 for periodic cleaning. Theheating means 60 is mounted preferably'above drying zones 32, 33, 34, 35and 36 and extends substantially the length of the drying chamber 10.

The heating chamber 60 is generally rectangular in shape and is providedwith top, bottom and side walls 61, 62, 63 and 64 and is bestillustrated in FIGS. 3, 4 and 6. Mounted within heating chamber 60 isheat exchanger 66 which extends over substantially the entire length ofdrying apparatus and is illustrated in side elevating in FIG. 6. Heatexchanger 66 is formed having an elongated tubular member 67 whichextends substantially the length of heating chamber 60 and is bent uponitself so as to form a serpentine path through I heating chamber 60.Heating unit 70 is mounted on entrance end 68 of tubular member 67 andmay be either an oil or gas fired burner which causes hot gases to flowthrough tubular member 67; through the discharge end 71 to pass the hotgases into chimney 72.

FIG. 4 is a top plan view of heating chamber and heat exchanger 66. Aplurality of tubular members comprise heat exchanger 66. Thus, at theentrant end 68 one or more heating units may be mounted thereto toprovide required amount of BTUs to uniformly heat fluid to a desiredpreset temperature. The fluid is preferably air although other gaseoussubstances may be employed so long as those substances, when heated,will uniformly dry a material such as a textile web. Obviously, manychanges in design are possible. However, each heat exchanger used isdesigned for a maximum output of BTUs. Also, the heating unit need notbe an oil or gas fired unit, it could be electric. A heated fluid suchas oil could be circulated through tubular members 67. Obviously thetype of heating unit and heat exchanger means will be dictated byeconomms.

The heating chamber 60 is provided with a pair of upstanding partitionor walls 63 and 64. Partition 63 is spaced from filters 47 to form aconduit or duct 72 for the passage of return air to be heated. Partition63 is rigidly mounted to bottom wall 62 of the heating chamber 60 andend wall 30 of drying apparatus 10 as illustrated in FIGS. 4 and 6. Theother end 73 of partition 63 is spaced from front wall 28 to provide anentrant opening 75 to heating chamber 60 for return air or fluid to beheated. Partition 64 is mounted in heating chamber 60 in a similarfashion as in partition 63. As illustrated in FIG. 4, the fluiddischarge opening 76 is diametrically disoosed from entrant opening 75so that all return air passing through entrant opening 75 into heatingchamber 60, as illustrated by the arrows in FIG. 4 will be uniformlyheated and subsequently pass through discharge opening 76 through fluiddistributing plenum 78 and into the intake opening of fan 50. Aplurality of fans 50 are provided, one for each drying zone 32, 33, 34,35 and 36 to move substantially equal volumes of uniformly heated fluidthrough each drying zone.

Fans 50 are mounted in opening 45 of partition 44 and are separated fromeach other by walls 41, 43, 45, 57 and 49 thus forming a compartmentmeans or fan duct 51 for passage of uniformly heated fluid dischargedfrom the heat exchanger to conduits 38 and 40 of drying zones 32, 33,34, 35 and 36. In conjunction with the flow of fluid through dryingapparatus 10, a by-pass fluid flow system may be employed and is shownin FIGS. 3 and 7-10. After the fluid has passed through openings 42 ofconduits 38 and 40 it is drawn to the discharge side of drying zone 32.A fluid by-pass duct 33 of drying zone 32 is formed by top wall 20,bottom wall 61 which is also the top wall of heating chamber 60, theupper portions of front and rear walls 28 and 30 and the upper portionsof side walls 24 and 26. Damper assembly 88 which may be manuallyor-automatically operated controls the amount of by-pass air which isfed into the heated air to maintain the desired uniform temperature. InFIG. 3, damper 88 is closed to ambient air and by-pass air. Thus, onlyuniformly heated air can pass through drying zone 32. In FIG. 7 amixture of by-pass and heated air is circulated through fan 50. In FIG.8, the damper position is similar to the damper position of FIG. 3. InFIG. 9 the damper functions as a 3-way valve in which a mixture ofoutside air, unheated return air and uniformly heated air from theexchanger is allowed to enter fan 50 for circulation through the dryingzone.

Positioned along the bottom wall 22 of drying apparatus 10 is exhaustduct I00. Exhaust damper 101 is pivotally mounted in exhaust duct andmay be manually or automatically operated to remove warm moist air.orfluid. Exhaust duct 100 is connected to exhaust stack or chimney 103. Amotor driven suction fan assembly 104 mounted on stack 103 establishesthe necessary exhaust pressure for removal of moist warm air from dryingapparatus 10. In practice, it has been found that moist exhausted airdischarged from drying zones 32 and 33 contains higher moisture contentthan exhausted air from drying zones 34, 35 and 36 and is thereforeremoved from the drying zones in greater volumes than exhaust air fromdrying zones 34, 35 and 36. About five complete air changes per minutemaintains a relative humidity of heated air which is suitable for dryingmaterial being passed through the drying chamber 10.

FIG. 7 schematically illustrates the temperature and fluid controlsystem of apparatus 10 for drying material. Drying zones 32, 33, 34, 35and 36 may be provided with temperature zone control means 80. Zonecontrol means may include temperature sensor bulb 82 connected to atemperature controller 84 which in turn is connected to damper operatordevice 86. Damper operator device 86 is connected to damper assembly 88which has means to direct fluid at ambient or near ambient temperatureinto intake opening of fan 50. By controlling the damper assembly anddirecting the proper amount of fluid or air into the drying zone,uniform fluid temperature may be maintained or, if desired, atemperature gradient may be maintained between each drying zone orzones.

Heat control means 90 maintains a constant desired temperature in theheat exchanger means 66 so that the fluid passing through the heatexchanger chamber 60 is heated uniformly and at a desired presettemperature. A temperature sensor bulb 92 is connected to temperaturecontroller 94 which is also connected to burner operator device 96.Burner operator device 96 is connected to heating unit 70. In operationtemperature controller 94 is set as a desired temperature so as tomaintain uniformly heated fluid or air being discharged from the heatingchamber 60. Temperature sensor bulb 92 will send a signal to temperaturecontroller 94 when the fluid temperature is below the desired presettemperature which, in turn, will cause heating unit 70 to operate.Likewise, when the desired temperature of the heated fluid is too high,a signal is transmitted from temperature sensor bulb 92 throughtemperature controller 94 which then causes heating unit 70 to shutdown. In this manner uniformly heated fluid is maintained to allowuniform drying of material M.

The damper assembly 88 is controlled in similar manner as heating unit70 by temperature sensor bulb 82 and temperature controller 84.

When operating drying apparatus 10 textile material M to be dried ismounted on pins 17 of tenter chains 16. Wet or moist material M is movedat about'2l0 to 300 feet per minute through drying apparatus 10 in whichuniformly heated air at about 300F. is continuously circulated throughdrying zones 32, 33, 34, 35 and 36. Heated air at 300F. is passed underpositive pressure from fan 50 through fan duct 51 and into conduits 38and 40 of drying zone 32, 33, 34, 35 and 36. Conduits 38 are mountedabove tenter chains and are positioned transversely of drying apparatus10. Conduits 40 are mounted similarly to conduits 38 but are positionedtransversely below the moving web material. Openings 42 formed inconduits 38 and 40 are spaced from each other in face to facerelationship so that heated or conditioned air being passed throughconduits 38 and 40 will contact the upper and lower surfaces of themoving web material M at approximately equal velocities and equalvolumes thus allowing textile material M to be passed through dryingapparatus 10 in a substantially weightless condition. It has beenobserved when textile material M is being passed through dryingapparatus 10 substantially no air passes through textile material M and,as a result, it appears to be floating through drying apparatus 10 on acushion of air with substantially no billowing of textile material M.The exhausted or spent heated air accumulates at the discharge side ofthe drying zone and is conducted upwardly through filters 47 and throughcommon entrant opening 75. The air is then caused to pass through andover heat exchanger means 67 so that the air passing out of the heatexchanger means will pass through common discharge opening 76 and beconducted along distributing conduit 78 to subsequently be drawn intothe intake opening of fans 50.

Fans 50 are controlled so that equal volumes of heated air, which havebeen heated to a predetermined preset temperature, are drawn throughfans 50 to be recycled through conduits 38 and 40 for continuouslydrying textile material M. In actual tests conducted using the dryingapparatus herein acetate textile material of 200 inches in width wasuniformly dried with substantially no temperature variation across thematerial and through the plurality of drying zones. The temperaturemeasured at the right, left and center showed temperature curvessubstantially identical. The temperature of the acetate material beforeentering was about 80F. along the right, left and center of the acetate.Almost immediately upon entering the first drying zone the temperatureuniformly rose to about 300F. and remained at this set temperature withless than about 10 variation throughout the entire drying time theacetate was passing through apparatus 10. Such runs are repro duciblefrom day to day and the temperature desired need only be preset to allowuniform drying over the entire surfaces of textile materials.

As described in FIGS. 7-9, the temperature of the air may be controlledby employing damper means 88. For example, if a desired temperaturewhich is different from the temperatures of the other drying zones isrequired, the damper means 88 of a particular fan 50 will be set forsensing the temperature required so that bypass air can be introducedinto the particular fan in question thereby effecting a temperaturegradient between drying zones.

ln FIG. 10 a damper means is mounted at the exit ends of conduits 38 and40 and may be either manually operated or automatically controlled. Adamper control device 112 is connected to damper means 110 and to thetenter machine. In the position as shown in FIG. 10 the damper controldevice would have caused a signal to be transmitted to the damperactuating means to cause the damper means to open since the tentermachine would have stopped. To avoid loss of fabric due to overheating,the dampers would cause the heated air to pass therethrough while only aminimum of heated air would pass through openings 42 of conduits 38 and40. At the same time, damper means 110 would be in the open positionoutside or ambient temperature air would be passed into drying apparatus10 to reduce the temperature thereof before being conducted through theapparatus.

While the invention herein has been described for drying a textilematerial, it should be understood that the drying apparatus may be usedfor drying films or other fibrous materials. Also, the heated air may beconditioned with other drying mediums such as superheated steam wheredesired.

It is apparent that many modifications may be accomplished and redesignof component parts of the ap paratus may be had without departing fromthe spirit and scope of the invention described herein.

We claim:

1. An apparatus for uniformly drying material comprising:

a generally rectangular drying chamber including side walls, a top wall,a bottom wall, front and rear walls;

said front and rear walls having horizontally extending openings forminga lined entrant and exit opening between the front and rear walls ofsaid chamher to define a pathway therebetween for the passage of thematerial to be dried therethrough;

an upstanding partition mounted in the drying chamber between said sidewalls;

a plurality of spaced parallel panels mounted transversely between saidupstanding partition and one of said side walls to form a plurality ofcompartment means;

a plurality of fluid supply means mounted in said drying chamber andbeing in fluid communication with each of said compartment means;

and means forming a plurality of drying zones in said chamber and spacedalong said pathway, each drying zone including at least a pair of spacedparallel conduits positioned above and below said pathway;

said conduits being mounted horizontally in said drying chamber andbeing in fluid communication with said compartment means;

a plurality of fluid supply openings of predetermined size and spacingin said conduits and said openings facing the pathway to provide auniform distribution of fluid to the entire surface of the material tobe dried in said chamber;

means forming a fluid heating chamber between the side walls andextending the length of the drying chamber and being in fluidcommunication with said compartment means and said pathway;

means placingsaid fluid heating chamber in communication with each ofsaid fluid supply means;

heat exchanger means disposed in said fluid heating chamber for heatingand conditioning the fluids to be distributed through the fluid supplymeans;

means forming an exhaust passageway being in fluid communication withsaid pathway to conduct the exhaust fluid through said fluid heatingchamber so that the heat exchanger means will uniformly heat the fluidprior to distributing the heated fluid through said fluid supply means;

a partition in said heating chamber extending from said rear wall andstopping just short of said front wall for directing all of the fluidfrom the exhaust passageway to the front of said heating chamber;

a further partition in said heating chamber extending from said frontwall and stopping just short of said rear wall for directing all of thefluid from said heating chamber to one end of a fluid distributingplenum formed between said further partition and said upstandingpartition to distribute heated fluid to said plurality of compartmentmeans.

2. The apparatus of claim 1 wherein the heat exchanger means comprises aplurality of elongated tubular members extending substantially theentire length of the heating chamber; heating means for heating theelongated tubular members, said heating means being mounted thereto.

3. The apparatus of claim 2 wherein the heating means is a gas firedburner in which the hot gases of combustion are conducted through theelongated tubular members so that fluid contacting the exterior surfacesof the tubular members is heated to a desired preset temperature.

4. The apparatus of claim 2 wherein the heating means is oil fired.

5. The apparatus of claim 1 wherein the fluid supply means forconducting heated fluid through said means forming a plurality of dryingzones comprises an unhoused fan.

6. The apparatus of claim 1 wherein said conduits include a fluid entryopening in fluid communication with said compartment means and anormally closed end, said closed end having damper means mounted thereonwhich is adapted to be opened to provide a heated fluid bypass toprevent said heated fluid from contacting the surfaces of the materialto be dried.

7. The apparatus of claim 1 wherein said means forming an exhaustpassageway includes filter means for filtering particulate material fromthe discharge fluid.

8. The apparatus of claim 1 wherein said drying chamber includes adischarge fluid exhaust conduit having damper means mounted thereon,said damper means being in fluid communication with said means forming acommon exhaust passageway for controlling the amount of discharge fluidexhausted therethrough. t III I i

1. An apparatus for uniformly drying material comprising: a generallyrectangular drying chamber including side walls, a top wall, a bottomwall, front and rear walls; said front and rear walls havinghorizontally extending openings forming a lined entrant and exit openingbetween the front and rear walls of said chamber to define a pathwaytherebetween for the passage of the material to be dried therethrough;an upstanding partition mounted in the drying chamber between said sidewalls; a plurality of spaced parallel panels mounted transverselybetween said upstanding partition and one of said side walls to form aplurality of compartment means; a plurality of fluid supply meansmounted in said drying chamber and being in fluid communication witheach of said compartment means; and means forming a plurality of dryingzones in said chamber and spaced along said pathway, each drying zoneincluding at least a pair of spaced parallel conduits positioned aboveand below said pathway; said conduits being mounted horizontally in saiddrying chamber and being in fluid communication with said compartmentmeans; a plurality of fluid supply openings of predetermined size andspacing in said conduits and said openings facing the pathway to providea uniform distribution of fluid to the entire surface of the material tobe dried in said chamber; means forming a fluid heating chamber betweenthe side walls and extending the length of the drying chamber and beiNgin fluid communication with said compartment means and said pathway;means placing said fluid heating chamber in communication with each ofsaid fluid supply means; heat exchanger means disposed in said fluidheating chamber for heating and conditioning the fluids to bedistributed through the fluid supply means; means forming an exhaustpassageway being in fluid communication with said pathway to conduct theexhaust fluid through said fluid heating chamber so that the heatexchanger means will uniformly heat the fluid prior to distributing theheated fluid through said fluid supply means; a partition in saidheating chamber extending from said rear wall and stopping just short ofsaid front wall for directing all of the fluid from the exhaustpassageway to the front of said heating chamber; a further partition insaid heating chamber extending from said front wall and stopping justshort of said rear wall for directing all of the fluid from said heatingchamber to one end of a fluid distributing plenum formed between saidfurther partition and said upstanding partition to distribute heatedfluid to said plurality of compartment means.
 2. The apparatus of claim1 wherein the heat exchanger means comprises a plurality of elongatedtubular members extending substantially the entire length of the heatingchamber; heating means for heating the elongated tubular members, saidheating means being mounted thereto.
 3. The apparatus of claim 2 whereinthe heating means is a gas fired burner in which the hot gases ofcombustion are conducted through the elongated tubular members so thatfluid contacting the exterior surfaces of the tubular members is heatedto a desired preset temperature.
 4. The apparatus of claim 2 wherein theheating means is oil fired.
 5. The apparatus of claim 1 wherein thefluid supply means for conducting heated fluid through said meansforming a plurality of drying zones comprises an unhoused fan.
 6. Theapparatus of claim 1 wherein said conduits include a fluid entry openingin fluid communication with said compartment means and a normally closedend, said closed end having damper means mounted thereon which isadapted to be opened to provide a heated fluid bypass to prevent saidheated fluid from contacting the surfaces of the material to be dried.7. The apparatus of claim 1 wherein said means forming an exhaustpassageway includes filter means for filtering particulate material fromthe discharge fluid.
 8. The apparatus of claim 1 wherein said dryingchamber includes a discharge fluid exhaust conduit having damper meansmounted thereon, said damper means being in fluid communication withsaid means forming a common exhaust passageway for controlling theamount of discharge fluid exhausted therethrough.